Advantages of nonionic contrast agents in adult urography

Nonionic radiographic contrast agents have a reported advantage of decreased contrast osmolality. Before clinical significance can be attributed to this lower osmolality, an observed difference must be documented. In a randomized double-blind study with 55 patients, Iohexol, a new nonionic contrast agent, is compared with Renografin 60 for use in adult urography. Hemodynamic parameters, serum and urine chemistries, including osmolality, were recorded before and after contrast injection. Radiographic quality and adverse reactions were recorded. This study focused on the change in urine osmolality (delta Osm) from pre- and post-injection urine specimens. The group receiving nonionic contrast agents had an average delta Osm of 65 mOsm/L while those receiving the ionic agent had an average delta Osm of 120 mOsm/L. This significant difference in urine osmolality is discussed with respect to the observed advantage in radiographic quality and the lower incidence of adverse reactions noted in the group receiving nonionic contrast material.